1. Technical Field
Exemplary embodiments of the present invention relate to a printed circuit board (PCB) and a semiconductor module including the same. More particularly, exemplary embodiments of the present invention relate to a PCB on which a semiconductor package is mounted and a semiconductor module including the same.
2. Description of the Related Art
Various types of semiconductor packages are being developed as applications thereof are continuing to expand. The semiconductor packages are becoming smaller and lighter in response to trends in forming miniaturized and high-speed semiconductor chips. In particular, the electrical properties of the semiconductor packages, which were less important in conventional low-speed operation, are becoming increasing important factors limiting the operation speeds of the semiconductor chips operating at high speeds.
Pins, which are elements of a semiconductor package, electrically connect the inside and the outside of the semiconductor chip, and electrical properties of the pins are key factors in high speed operation. Thus, various semiconductor package structures according to the physical structures and arrangement methods of the pins have been proposed. Nowadays, a ball grid array (BGA) packages, chip scale packages (CSPs), flip-chip packages, etc. are universally used.
In particular, a BGA package has excellent features in terms of density and general purpose use. The BGA package may use a laminated printed circuit board (PCB) as a substrate for manufacturing a semiconductor module of a multi-chip module type and may include a plurality of conductive pads for electrical connections with a motherboard, a back plane, an application board, and so on. In the BGA package, a solder ball such as a BGA is used for an electrical connection. Generally, the above-mentioned semiconductor modules using the laminated PCB having organic material are called plastic BGAs.
PCBs now also have fine patterns, and have become smaller and packaged in response to the trend in forming miniaturized semiconductor packages. The demand for integrated and miniaturized circuits of the PCBs as well as changes in raw material is increasing to manufacture a PCB having a high degree of integration and reliability. Accordingly, a multilayer PCB including an inner layer and an outer layer may be used to expand a wiring region of the PCB.
Conventionally, conductive lines, such as traces for a power line or a signal line crossing over a mounting region of the semiconductor package, are disposed in the inner layer of the PCB. However, because nowadays various semiconductor packages are mounted on the PCB and kinds of the power and signal lines are increasing, spaces for routing the traces in the inner layer of the PCB are becoming insufficient. Therefore, spaces for routing the traces on the outer layer where the semiconductor package is mounted are needed.